In many instances, it is desirable to supervise or detect movement of objects or articles from their proper location. For example, sprinkler systems have been installed in many public and private buildings to help control fires from spreading. These sprinkler systems usually have control valves located in a number of easily accessible areas and may be opened or closed by passing individuals. As a result, these control valves are vulnerable to tampering by unauthorized personnel or may be inadvertently closed. Hence, the sprinkler system may not operate properly allowing a fire which might otherwise be easily contained to spread beyond control. Thus, it is desirable to monitor the status of such valves.
Prior art devices have been developed to initiate an alarm when a sprinkler system control valve is closed. A known device can be used to monitor a handwheel-type valve of a sprinkler system. The device is mounted by a mounting bracket to a structural member adjacent to the handwheel to be supervised. The device has a conventional male plug with two flat, parallel prong-type contacts that are insertable into a freely movable receptacle in a closed housing.
An alarm is activated when the handwheel of the sprinkler system is turned disconnecting the plug from the receptacle. When installing the device, the installer cuts a conductor to the appropriate length and loops the conductor around the handle of the valve. The conductor is then attached to the hook-up terminals of the plug.
Known types of such devices are not rated for external installation. In addition, the known devices are rated for Class B-type wiring only.
Accordingly, there is a need for an improved apparatus to supervise movable articles or objects. It would be desirable if the apparatus was easily installed and operated. It would also be desirable if the apparatus was suitable for exterior installation and if it could be wired for Class A operation.